Continiuous, In-Line pH Measurement in Hot, Undiluted Ammonium Nitrate

During storage, ammonium nitrate pH control plays an important role in the prevention of decomposition and ammonia loss. However, due to the high temperature, high pressure, and high concentration, ammonium nitrate pH measurement during storage can quickly cause a pH sensor to expire. This application note addresses the importance of pH measurement in ammonium nitrate storage.

Ammonium nitrate is a solution that can be further processed into a dried or granulated product. It can be used as a fertilizer on its own, or can be blended with other products. For safety reasons it is often stored as a liquid instead of a solid crystal. Ammonium nitrate pH measurement is an important part of the process of maintaining the compound in its liquid state. Ammonium nitrate pH levels need to stay neutral or alkaline to prevent the acidic conditions that enhance decomposition. But ammonium nitrate must also be stored at very high temperatures to prevent crystallization. At high concentrations, temperatures regularly need to be above 120°C to stop the liquid ammonium nitrate from crystalizing in the storage vessel.

The problem is that the high storage temperature causes many standard pH sensors to have a very short lifespan. Sensor lifetimes of less than one week in this environment are common.

This application note addresses these topics, and proposes a way to prevent sensor failure or the need to implement costly concentration systems for the measurement of ammonium nitrate pH during storage.